Prefabricated building panels are a popular implement in today's construction industry, especially for commercial applications. Labor time and costs associated with welding and bolting, for example, significantly increase the cost of traditional construction whereby individual materials (e.g., external siding, insulation, support framing, etc.) are generally arranged and assembled at the job site. Mixing concrete at the job site includes labor costs as well as down time to permit the concrete to set. These and similar costs have been somewhat reduced in recent years by the development and increased use of precast concrete and, in particular, prefabricated building panels which combine precast concrete with other materials such as insulation and support framing. These panels are generally built and assembled at an off site location and then transported to the construction site, ready for installation. At the job site, the panels are hoisted and moved into position on the incomplete building structure. Once in position, construction workers may then bolt and/or weld the panels to the building frame and/or floor and to one another to fix them in their final locations.
Despite the advantages identified above, known prefabricated building panels are far from ideal. Existing panels tend to be very heavy, typically in the range of 90 lbs per square foot, and in all cases require heavy machinery such as cranes to lift and maneuver at the job site. In general, the design of prefabricated building panels is a challenging puzzle of inseparable pros and cons. For example, in order to support the weight of itself and potentially other building elements (e.g., roofing, neighboring panels, etc.), the concrete must be quite thick, generally 6 or more inches. The height of many present day commercial buildings means wind speeds also become a critical consideration and further require increased material thicknesses for greater strength. While thicker concrete improves the strength of a panel, it obvious greatly increases the weight and volume of the panel, both effects being highly undesirable.
Newer energy codes for buildings, especially renovations and new construction, continue to set more stringent performance criteria. As new codes go into effect, the construction industry is faced with a need for new alternatives which strike the difficult balance of such factors as weight, size (e.g., panel thickness), thermal insulation, strength (e.g., as measured in psi or maximum incident wind speed), and material costs.